Time to replace HVAC - thoughts on options?

[travelover]

The two stage / variable speed compressor is nice for dehumidification. It solves the problem of the trade off for sizing for maximum load conditions vs maximum run time, which is good for dehumidifying. At my last home, the heavy tree coverage made humidity a priority over raw heat removal in the summer. The down side is initial cost and potential repair cost. It also makes the heating more even as the fan runs more, distributing the heat.

[stephenson]

Most Manual J Load Software is expensive, but I found a site that runs a basic heat-cool calc ... these used to be big spreadsheets, but now are likely more accurate with potentially more and more variables as the software model improves ... here's what my calc says.

I think one normally sizes for A/C load and uses the backup gas/electric for those few times (in our area) that the A/C running backwards in heat pump, won't keep up.

Load divided by 12K BTU gives the tonnage.

Texas Proud - I think you can have single speed compressor and option for multi speed fan, but if you have multi speed compressor, you must have multi speed fan?